On Fri, 10 Oct 1997, Clyde Smith-Stubbs wrote:

> On Fri, Oct 10, 1997 at 08:48:33AM -0700, Scott Walsh wrote:
>
> >      Also, is anybody familiar with the term 'condensor microphone' that
> >      used to be on old tape recorders?
>
> Yes, it was a precursor to the current electret microphone. It consisted of
> a pair of plates arranged as an air-spaced capacitor (aka condensor)
> biased by a high voltage. One plate vibrated with the sound waves, resulting
> in a AC signal superimposed on the bias voltage.
>
PTM: I have used this kind of systems to measure pressure.

--------------------------------------------------------------------------
PTM, pasi.mustalahti@utu.fi, ptmusta@utu.fi, http://www.utu.fi/~ptmusta
Lab.ins. (mikrotuki) ATK-keskus/Mat.Luon.Tdk                    OH1HEK
Lab.engineer (PC support) Computer Center                       OI7234
Mail: Turun Yliopisto / Fysla, Vesilinnantie 5, 20014
Pt 02-3336669, FAX 02-3335632 (Pk 02-2387010, NMT 049-555577)
--------------------------------------------------------------------------